As a solid catalyst component for olefin polymerization, spherical magnesium alcoholates having an average particle diameter of 60 μm or more, a less number of fine particles, and a sufficient strength have been desired. As a method for producing such magnesium alcoholates, for example, there is a method disclosed in Patent Document 1 that the final ratio of the metallic magnesium and alcohol used in the reaction system is from 1/4 to 1/25 in mass ratio, and that particulate metallic magnesium having a diameter of not more than 500 μm and the alcohol are added continuously or intermittently in a portionwise manner to the reaction system under alcohol reflux and allowed to react for 100 to 1,200 minutes. In addition, in this method, it has been described that it is preferable to carry out the addition of each of the metallic magnesium and alcohol in 10 or more separate portions, and also in a manner so that the intervals of addition is a combination of intervals selected arbitrarily from the range of 10 to 120 minutes and the total addition time is within the range of not more than 1,200 minutes. It has been described that by using this method, particulate matter of dialkoxymagnesium having spherical or ellipsoidal particle shapes with an average particle diameter represented by D50 in the range of 60 to 200 μm, a bulk specific gravity of 0.2 to 0.7 g/ml, numerous internal pores with pore sizes from 0.1 to 5 μm as determined by TEM observation, and a particle size distribution represented by (D90−D10)/D50 of not more than 1, can be obtained, and the breaking strength of the aggregated particulate matter is from 0.5 to 10 MPa. It has been described that in the synthetic reaction according to this method, the use of a catalyst is preferred, while listing iodine and the like as examples of useful catalysts, and moreover, this catalyst may be initially added collectively to the reaction system or may be added while adjusting the amount in accordance with the portionwise addition of raw materials.
Further, it has been disclosed in Patent Document 2 that by reacting metallic magnesium, an alcohol, and 0.0001 gram atom or more of a halogen or halogen-containing compound containing a halogen, relative to one gram atom of the above metallic magnesium, it is possible to produce an alkoxy group-containing magnesium compound having an average particle diameter from 1 to 300 μm and also a particle size distribution index (P) represented by the following formula (1) of P<5.0 which indicates a narrow particle size distribution, and which can be used as it is without particle size adjusting treatments such as pulverization and classification (formula (1): P=D90/D10, where D90 denotes a particle diameter corresponding to the cumulative weight fraction of 90%, and D10 denotes a particle diameter corresponding to the cumulative weight fraction of 10%). In this document, it has been described that there is no need to introduce the total amount of each of metallic magnesium, an alcohol, and a halogen and/or halogen-containing compound into a reaction tank from the beginning, and the introduction may be conducted in separate portions.